1. Field of the Invention
The present invention relates to a processing device that bonds paper sheets carried out from an image forming device, such as a copying machine or a printer, to form a paper sheet bundle and to a device capable of processing paper sheets successively delivered.
2. Description of the Related Art
A sheet processing device that aligns paper sheets delivered from an image forming device and staples the paper sheets or folds the paper sheets in a booklet form is widely known. Such a sheet processing device is provided with a plurality of sheet storage means for sheet post-processing. For example, in a first sheet storage means, the paper sheets are stored in a bundle and are then stapled and, in a second sheet storage means, the paper sheets stored in a bundle are subjected to saddle stitching and then folded in a booklet form. In recent years, a binding processor that binds a paper sheet bundle without use of a metallic binding needle (metallic staple) in the sheet bundle binding processing and a sheet processing device that uses the binding processor are being provided.
For example, Jpn. Pat. Appln. Laid-Open Publication No. 2011-201698 discloses a device that performs bookbinding without use of a metallic binding staple so as to enhance recyclability and safety of the bound paper sheets. In this device, a folding plate and a folding roller pair apply folding to a paper sheet bundle stored in a stacker for storing a plurality of paper sheets in order. A binding mechanism section binds the paper sheet bundle, without use of the metallic staple, in a position at a predetermined interval from a folding position where the paper sheet bundle is subjected to folding by the folding plate and the folding roller pair.
In the binding processing, the binding mechanism section causes deformation in a thickness direction of the paper sheet bundle that has been subjected to folding by the folding plate and the folding roller pair so as to bind the paper sheet bundle. More specifically, upper and lower concave-convex crimping teeth are meshed with each other to cause local deformation in the thickness direction of the paper sheet bundle to make the paper sheets to be engaged with each other (see FIGS. 4 and 5 of Jpn. Pat. Appin. Laid-Open Publication No. 2011-201698).
A portion to which the binding mechanism applies binding is set so as to be separated by a predetermined interval from the folding position of the paper sheet bundle (see FIGS. 7 and 11 of Jpn. Pat. Appin. Laid-Open Publication No. 2011-201698). In other words, the folding position and binding position are shifted from each other.
On the other hand, U.S. Patent Application Publication No. 2013/0133837 (corresponding to Jpn. Pat. Appin. Laid-Open Publication No. 2013-112527) discloses technology that applies a heat sensitive adhesive to paper sheets for bonding to obtain a paper sheet bundle. In this invention, an application section that applies the adhesive is provided at a sheet processing device entrance which is located on an upstream side relative to a sheet processing section that stores the paper sheets in a sheet conveying direction. The application section applies the adhesive to one surface or both surfaces of the carried paper sheet at a portion to be folded. The resultant paper sheet is conveyed along a comparatively long conveying path to a stacker section for sheet storage by means of several stages of conveying rollers. After conveyance to the stacker section, the adhesive-applied positions of the paper sheets are pressurized by a pressure roller to form a paper sheet bundle. Then, the obtained paper sheet bundle is pushed to a folding roller by a folding blade for folding processing.
Further, Japanese Patent No. 5,168,474 discloses a bookbinding device provided with a unit housing section that can alternatively houses one of a needle binding unit that applies a needle binding processing to a paper sheet bundle and a paste binding unit that applies pasting onto the paper sheets and pressure-bonds them to form a paper sheet bundle. To this end, the needle binding unit and paste binding unit are set so as to be detachably attached to the unit housing section. Further, this device includes a folding section that folds the paper sheet bundle bound by one of the above units in two.
Further, Japanese Patent No. 5,382,597 discloses a device provided with a paste binding unit that applies pasting onto the paper sheets and pressure-bonds them to form a paper sheet bundle and a needle binding unit that performs a needle binding processing. The device alternatively executes the paste binding and needle binding and then executes folding processing. With this configuration, a booklet can be created by paste binding or needle binding according to the need.
In the device that aligns paper sheets carried out from an image forming device or the like for subsequent binding processing and/or folding, when the paper sheet bundle is formed without use of the metallic staple or by bonding the paper sheets, the following problems arise.
The invention disclosed in Jpn. Pat. Appin. Laid-Open Publications No. 2011-201698 is configured to bind the paper sheet bundle by deforming the paper sheets themselves. For example, upper and lower concave-convex crimping teeth are meshed with each other to cause local deformation in the thickness direction of the paper sheet bundle to make the paper sheets to be engaged with each other. However, it is necessary to mesh the upper and lower concave-convex crimping teeth with a considerable crimping force in order to make the paper sheets to be engaged with each other. An insufficient crimping force results in insufficient binding, that is, only the crimping force cannot make the binding state stable. When the binding position is made to coincide with the folding position in this crimping system, a deformation force due to curve of the paper sheets acts to affect binding performance.
Further, as another binding mechanism, there is known a mechanism including a cut forming section that forms a cut bent in a convex shape on one side of a paper sheet bundle and a binding portion forming section that forms, inside a range surrounded by the convex-shaped cut, a binding portion for binding the paper sheet bundle, wherein the convex-shaped cut is inserted into the binding portion for binding. In this case, a comparatively large cut is formed in the paper sheets themselves, so that damage is given to the paper sheets themselves, and outer appearance is affected.
Under such circumstances, as disclosed in U.S. Patent Application Publication No. 2013/0133837 (corresponding to Jpn. Pat. Appin. Laid-Open Publication No. 2013-112527), the binding mechanism that binds the paper sheet bundle using an adhesive without use of the crimping mechanism or without forming large cut in the paper sheets can be considered effective.
However, in this mechanism, the paper sheet is conveyed along a comparatively long conveying path to a stacker section for sheet storage by means of several stages of conveying rollers, as described above. That is, the sheet applied with an adhesive at the device entrance is conveyed to the stacker section along the comparatively long conveying path through several conveying rollers, so that a sheet jam may occur due to undesired adhesion of the adhesive to surroundings of the conveying path.
Further, the adhesive-applied paper sheets stored in the stacker section for bonding are not necessarily aligned with one another, and the paper sheet may be folded in a mutually misaligned state. In addition, in order to prevent the adhesive from being adhered to the surroundings of the long conveying path, it is necessary to select, as a pressure sensitive tape used as the adhesive, one that does not exhibit adhesive power until it receives a significant pressure. That is, it is necessary to carefully select the adhesive to be used and to use a special pressurizing mechanism.
On the other hand, in the device disclosed in Japanese Patent No. 5,168,474, one of the needle binding unit and paste binding unit can be attached to the unit housing section of the device. In this configuration, when the paste binding unit is selected to perform pasting, a paper sheet is carried in the unit with a pasting surface (bonding surface) of a preceding paper sheet being exposed, so that the paper sheets may be bonded to each other at an unintended portion. Further, the paper sheet after the pasting is conveyed to a folding device by a distance two or more times a sheet length, so that the adhesive may be adhered to the device component.
In the device disclosed in Japanese Patent No. 5,382,597, the paste binding unit and needle binding unit are arranged side by side in the sheet conveying path. Although the paper sheet is conveyed by a suction feeding mechanism in this device, a paper sheet (second paper sheet) is carried in the unit with a pasting surface (bonding surface) of a preceding paper sheet (first paper sheet) being exposed as in the paste binding unit disclosed in Japanese Patent No. 5,168,474. Therefore, for example, a leading end of the second paper sheet to be carried in may be brought into contact with the adhesive on the first paper sheet, with the result that the paper sheets may be bonded to each other at an unintended portion. Further, also in this device, the paper sheet after the pasting is conveyed to an inside of the device by a distance two or more times a sheet length, so that the adhesive may be adhered to the device component.
The present invention has been made in view of the above problems, and an object thereof is to provide a comparatively small sheet processing device capable of forming a paper sheet bundle by bonding the paper sheets using an adhesive to reduce stress to be applied to the paper sheet as compared to a case where the paper sheet bundle is bound with a metallic staple or by deforming the paper sheets themselves, capable of comparatively reducing movement of the paper sheet applied with the adhesive to prevent the adhesive from being adhered to a portion other than the paper sheet in the conveying path or stacker section, and capable of reliably bonding the paper sheets through the adhesive at a predetermined position while suppressing the adhesive from being adhered to an unnecessary portion, an image forming device provided with the sheet processing device, and a sheet bonding method.